In petroleum wells, sliding piston sleeve actuators are often used for many purposes. In such wells it is important that pockets, created in the annular spaces between the sleeves and the tubular members with which they coact, not be filled with liquid which would result in a hydraulic lock preventing proper operation of the moving sleeve. The present invention relates to an improved sleeve actuator in which the cavity between the sleeve and the tubular member with which it coacts excludes the well liquids from entry therein so that hydraulic lock does not prevent proper operation.
U.S. Pat. No. 4,662,663 discloses a method and apparatus for the forming of one tubular member of a subsea pipeline into another tubular member having internal lands and grooves for receiving the formed member and provides for the filling of the grooves with a structure which compensates for the pressure which tends to build during the forming step. This patent suggests the use of a gas filled tube or the use of a material which is composed of a plurality of microspheres in an epoxy matrix. This material is described in such patent as being suitable to exclude sufficient liquid (sea water) from the grooves so that when the inner tubular member is formed therein that the material collapses to prevent any pressure build-up in the grooves which would interfere with the proper completion of the forming step.